DESERT DINGHY

FIRST the horse, and now the camel - no beast is safe from the relentless advance of mechanization.  Threatening the omnipotence of the Ship of the Desert in the sandy wastes of the Sahara is a new twin-engined Citroen project, the 2 c.v. Saharienne. Like the camel, it has four powered contact points with terra  infirma, but it moves faster and carries more passengers more comfortably. So far only one of these ubiquitous vehicles has been made, and the Quai de Javel will assess public and commercial reactions and opinions before proceeding with its production.

Outwardly the Saharienne looks like a standard export model; that is, its suspension is set to give slightly more ground clearance, its protective undertray is extended and swept upward front and rear, to meet bumpers which have an increased clearance longitudinally from the body ends. Under the front bonnet an oil-bath air filter to the carburettor is noticed. Inside the passenger compartment there are the usual clutch, brake and accelerator pedals and the normal facia-mounted gear lever. Between the front seats, however, is a second ignition switch and starter control, and the floor of the rear compartment is divided by a narrow pressing covering extra control links.

It is in the boot that the non-conformity really becomes apparent, for a second engine/transmission unit is tucked away within it. This is identical with the standard front-drive assembly (425 c.c. air-coooled four-stroke, flat twin engine, in unit with a centrifugal disc clutch, four speed gearbox and final drive)and includes the inboard drum brakes. It is however, installed with the engine behind the transmission, so that the two units are symmetrical about the car’s transverse axis. This has entailed only one modification of the drive assembly-placing the final drive crownwheel on the opposite side of its driving pinion to give it reversed rotation.

It will be remembered that the 2 c.v.’s interacting-type suspension is symmetrical in standard form, the front wheels being carried on leading and the rear on trailing arms.  The front and rear arms on each side are linked by adjustable tension rods to a common coil spring assembly, mounted midway along the side of the chassis platform. Thus, the four-wheel-drive installation has necessitated no alterations to the suspension layout or characteristics.

Under normal road conditions and on firm ground the Saharienne is intended to be pulled along by its front engine and wheels alone, and there is no direct transmission link between front and rear. In heavy going, such as in mud or soft, yielding sand, or when tackling steep gradients with a full load, the rear engine is started and thereafter controlled by the common clutch and throttle pedals, and gear lever. This arrangement doubles not only its tractive means but also its collective power-from 14 to 28 nett b.h.p. The dry weight is no more than 1,430 lb (12 3/4 cwt, 650 kg), and its fore and aft distribution is claimed to be practically 50/50 regardless of the load carried.

Until the rear engine is started it remains isolated from its transmission by virtue of the centrifugal clutch. Even when this engine is not running, its throttle valve is being operated and its gears changed. In practice there seem to be no difficulties about changing gears in the ‚”dead” box, since there is synchromesh on the three upper ratios, and in any case the inertia of the small gear wheels is very low. Any desired interrelation between the throttle settings can, of course, be arranged, but as demonstrated they appeared to be identical.

To witness the capabilities of the Saharienne I was invited last Friday to join a number of French journalists at La Mer de Sable, a strange little desert of fine yellow sand in the middle of the Forest of Compiegne, near Ermenonville, about 30 miles north-east of Paris. It is here, incidentally, that the poet Jean-Jacques Rousseau lies buried in the beautiful grounds of his beloved Chateau de Chaalis. Contrasting with the little grey 2 c.v. demonstration car were two rather disdainful real live camels, one of which was also subjected to a brief road test by your reporter.

Although tyres of abnormally large section for this model were fitted to the Citroen-155 in place of 135 x 400-these were standard Michelin X covers with the ordinary tread pattern. They were inflated to 10 lb sq in (0.7 kg), which is the pressure recommended for everyday use on tarmac roads.

The Sea of Sand was soft and damp - even a little snow fell while the Citroen performed its astonishing evolutions; but even with four up it proved able to overcome the drag of sand which made walking quite a labour, and attacked slopes of about 1 in 3 on the same surface. The relatively low weight is a great advantage.

One obvious advantage of the Saharienne’s tractive means over other four-wheel-drive vehicles is the independence of its front and rear systems; this not only permits the wheels to tum at different speeds without fore-and-aft torque transference, but seems also to reduce the snaking tendency experienced with some coupled drives.

Extreme flexibility and range of the unique Citroen suspension allows the car to be driven over ridged sand and deeper inequalities without shock to the occupants, although if these are taken too fast it more nearly approaches the slow-motion pitch and roll of a camel ride. This flexibility ensures also that the wheels follow the contours of the ground, and absence of hop removes one incitement to wheelspin.

As an inexpensive means of travelling comfortably and surely over terrain which hitherto has been impassable to all but relatively costly and complicated special-purpose vehicles, the Saharienne offers increased mobility to oil prospectors, archaeologists, explorers and the like. It really works-and it's fun!

R. B.